U.S. patent number 7,339,623 [Application Number 10/300,728] was granted by the patent office on 2008-03-04 for camera and image pickup device unit which reduce influence of dust image quality.
This patent grant is currently assigned to Olympus Optical Co., Ltd.. Invention is credited to Sumio Kawai.
United States Patent |
7,339,623 |
Kawai |
March 4, 2008 |
Camera and image pickup device unit which reduce influence of dust
image quality
Abstract
A camera is provided which includes a dust-proofing member
having a substantially circular or polygonal plate-shape and a
transparent portion at an area having at least a predetermined
length in a radial direction from a center of the dust-proofing
member. The transparent portion is opposed to a front of an optical
device at a predetermined interval, and an interval of an
equivalent optical path length of at least 5 mm is provided between
a surface of the dust-proofing member and the photoelectrically
converting surface of the image pick-up device. And a sealing
structure portion is arranged at a portion formed by opposing the
image pick-up device and the dust-proofing member. The sealing
structure seals a space portion that is substantially sealed at
peripheral portions of the image pick-up device and the
dust-proofing member.
Inventors: |
Kawai; Sumio (Hachioji,
JP) |
Assignee: |
Olympus Optical Co., Ltd.
(Tokyo, JP)
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Family
ID: |
29545419 |
Appl.
No.: |
10/300,728 |
Filed: |
November 20, 2002 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20030218685 A1 |
Nov 27, 2003 |
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Foreign Application Priority Data
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May 27, 2002 [JP] |
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2002-153018 |
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Current U.S.
Class: |
348/340; 348/374;
348/E5.028 |
Current CPC
Class: |
H04N
5/2254 (20130101); H04N 5/22521 (20180801) |
Current International
Class: |
H04N
5/225 (20060101) |
Field of
Search: |
;348/335,340,357,374 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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57-078032 |
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May 1982 |
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JP |
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58-152201 |
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59-006399 |
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62-165127 |
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JP |
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63-009970 |
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63-131498 |
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JP |
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01-230016 |
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02-001699 |
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2-065369 |
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02-132860 |
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JP |
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03-244281 |
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JP |
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4-047769 |
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JP |
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19920217 |
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04-104918 |
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05-167051 |
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05-213286 |
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07-151946 |
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07-151946 |
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7-222068 |
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JP |
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07-322153 |
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JP |
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07-322153 |
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7-322153 |
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JP |
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H07-322153 |
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08-079633 |
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Mar 1996 |
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JP |
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08-079633 |
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JP |
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HEI 8-79633 |
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Mar 1996 |
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JP |
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09-124366 |
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JP |
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09-130654 |
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JP |
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2809133 |
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Jul 1998 |
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JP |
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10-268129 |
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Oct 1998 |
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JP |
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2000-029132 |
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Jan 2000 |
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JP |
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2000-066021 |
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Mar 2000 |
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JP |
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2000-124519 |
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Apr 2000 |
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JP |
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2000-330054 |
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Nov 2000 |
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JP |
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2001-298640 |
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Oct 2001 |
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JP |
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2001-345392 |
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Dec 2001 |
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JP |
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2001-358287 |
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Dec 2001 |
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JP |
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2001-358974 |
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Dec 2001 |
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JP |
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2002-050751 |
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Feb 2002 |
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JP |
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2002-107612 |
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Apr 2002 |
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JP |
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2002-204379 |
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Jul 2002 |
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JP |
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2002-229110 |
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Aug 2002 |
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JP |
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2003-333391 |
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Nov 2003 |
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JP |
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Other References
Takizawa et al., U.S. Appl. No. 10/300,688, Nov. 20, 2002. cited by
examiner.
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Primary Examiner: Ho; Tuan
Assistant Examiner: Bemben; Richard M.
Attorney, Agent or Firm: Frishauf, Holtz, Goodman &
Chick, P.C.
Claims
What is claimed is:
1. A camera comprising: an image pick-up device which obtains an
image signal corresponding to beams irradiated onto a
photoelectrically converting surface thereof; an exchangeable
photographing lens which inputs a subject image onto the
photoelectrically converting surface of the image pick-up device;
an image signal processing circuit which converts an image signal
obtained from the image pick-up device, corresponding to an image
formed onto the photoelectrically converting surface of the image
pick-up device, into a signal suitable to recording; a
dust-proofing member having a substantially circular or polygonal
plate-shape and comprising a transparent portion at an area having
at least a predetermined length in a radial direction from a center
of the dust-proofing member, wherein the transparent portion is
opposed to a front of the photographing lens at a predetermined
interval, and wherein an interval of an equivalent optical path
length of at least 5 mm is provided between a surface of the
dust-proofing member and the photoelectrically converting surface
of the image pick-up device; a vibration generating member, for
vibrating the dust-proofing member, arranged outside an area
through which the beams pass through the dust-proofing member,
wherein the vibration generating member includes a piezoelectric
element made of piezoelectric ceramics; and a sealing structure
portion arranged at a portion formed by opposing the image pick-up
device and the dust-proofing member, the sealing structure portion
sealing a space portion that is substantially sealed at peripheral
portions of the image pick-up device and the dust-proofing
member.
2. The camera according to claim 1, wherein the vibration
generating member causes the dust-proofing member to vibrate in a
standing wave.
3. The camera according to claim 1, wherein the dust-proofing
member comprises an optical low-pass filter.
4. The camera according to claim 1, wherein the dust-proofing
member comprises an infrared cut-off filter.
5. The camera according to claim 1, wherein the dust-proofing
member comprises a protecting glass of the image pick-up
device.
6. The camera according to claim 1, wherein an optical low-pass
filter is arranged between the image pick-up device and the
dust-proofing member.
7. The camera according to claim 1, wherein an infrared-cut-off
filter is arranged between the image pick-up device and the
dust-proofing member.
8. A camera comprising: an image pick-up device which obtains an
image signal corresponding to beams irradiated onto a
photoelectrically converting surface thereof; an optical member
having a first surface opposed to a front of the image pick-up
device at a predetermined interval; and a sealing structure portion
arranged at a portion formed by opposing the image pick-up device
and the optical member, the sealing structure portion sealing a
space portion that is substantially sealed at peripheral portions
of the image pick-up device and the optical member, wherein a
dimension of an interval between the photoelectrically converting
surface of the image pick-up device and a second surface of the
optical member is set such that when positioning an object having a
diameter of 1/10 or less of an exit pupil of a photographing lens
on the second surface of the optical member, a density of a shade
formed onto the photoelectrically converting surface is
approximately 5% or less of a density of a shade formed by the
object when placing the second surface of the optical member at a
position of an equivalent optical path length of 1 mm in air from
the photoelectrically converting surface.
9. The camera according to claim 8, wherein a dimension of the
interval has an equivalent optical path length of 5 mm or more in
air.
10. The camera according to claim 8, further comprising: a
vibration generating member arranged at the peripheral portion of
the optical member for vibrating the optical member.
11. An image pick-up device unit comprising: an image pick-up
device which obtains an image signal corresponding to beams
irradiated onto a photoelectrically converting surface thereof; an
optical member having a first surface opposed to a front of the
image pick-up device at a predetermined interval; and a sealing
structure portion arranged at a portion formed by opposing the
image pick-up device and the optical member, and the sealing
structure portion sealing a space portion that is substantially
sealed at peripheral portions of the image pick-up device and the
optical member, wherein a condition for preventing formation of an
original shade of an object onto a second surface of the optical
member is set to establish a relationship of an equivalent optical
path length L in air between the object and the photoelectrically
converting surface of the image pick-up device, such that:
L>A.times.d/D where a diameter of an exit pupil of a
photographing lens is designated by D, a diameter of the object is
d, and an equivalent optical path length in air from a position of
the exit pupil to the photoelectrically converting surface of the
image pick-up device is designated by A.
12. The image pick-up device unit according to claim 11, further
comprising: a vibration generating member arranged at the
peripheral portion of the optical member for vibrating the optical
member.
13. An image pick-up device unit applicable to a camera to which a
photographing lens is exchangeably attached, said image pick-up
unit comprising: an image pick-up device which obtains an image
signal corresponding to beams irradiated onto a photoelectrically
converting surface thereof; a plate-shaped optical member having a
first surface opposed to a front of the image pick-up device at a
predetermined interval; a vibration generating member, for
vibrating the optical member, arranged outside an area through
which the beams pass to be irradiated onto the photoelectrically
converting surface of the image pick-up device, wherein the
vibration generating member includes a piezoelectric element made
of piezoelectric ceramics; and a sealing structure portion arranged
at a portion formed by opposing the image pick-up device and the
optical member, the sealing structure portion sealing a space
portion that is substantially sealed at peripheral portions of the
image pick-up device and the optical member, wherein an interval
between the photoelectrically converting surface of the image
pick-up device and a second surface of the optical member is set
such that when a non-transparent object having a diameter of not
more than 50 .mu.m is positioned on the second surface of the
optical member, a shade density of a shade of the object on the
photoelectrically converting surface of the image pick-up device is
not more than 5%.
14. A camera comprising: an exchangeable photographing lens; an
image pick-up device which obtains an image signal corresponding to
beams irradiated onto a photoelectrically converting surface
thereof; a plate-shaped optical member having a first surface
opposed to a front of the image pick-up device at a predetermined
interval; a vibration generating member, for vibrating the optical
member, arranged outside an area through which the beams pass to be
irradiated onto the photoelectrically converting surface of the
image pick-up device, wherein the vibration generating member
includes a piezoelectric element made of piezoelectric ceramics;
and a sealing structure portion arranged at a portion formed by
opposing the image pick-up device and the optical member, the
sealing structure portion sealing a space portion that is
substantially sealed at peripheral portions of the image pick-up
device and the optical member, wherein an interval between the
photoelectrically converting surface of the image pick-up device
and a second surface of the optical member is set to have a
dimension such that when a non-transparent object having a diameter
of not more than 50 .mu.m is positioned on the second surface of
the optical member, a shade density of a shade of the object on the
photoelectrically converting surface of the image pick-up device is
not more than 5%.
15. The camera according to claim 14, wherein the dimension of the
interval is determined based on a size of an exit pupil of the
photographing lens.
16. The camera according to claim 14, wherein the dimension of the
interval is determined based on a focusing distance of the
photographing lens.
17. The camera according to claim 14, wherein the dimension of the
interval is determined based on a distance from a position of the
exit pupil of the photographing lens to the photoelectrically
converting surface of the image pick-up device.
18. The camera according to claim 14, wherein the dimension of the
interval is determined based on a size of an exit pupil of the
photographing lens, a focusing distance of the photographing lens,
and a distance from a position of an exit pupil of the
photographing lens to the photoelectrically converting surface of
the image pick-up device.
19. The camera according to claim 14, wherein the dimension of the
interval is determined based on a pixel interval of the image
pick-up device.
20. An image pick-up device unit applicable to a camera to which a
photographing lens is exchangeably attached, said image pick-up
unit comprising: an image pick-up device which obtains an image
signal corresponding to beams irradiated onto a photoelectrically
converting surface thereof; a dust-proofing member having a
substantially circular or polygonal plate-shape and comprising a
transparent portion at an area having at least a predetermined
length in a radial direction from a center of the dust-proofing
member, wherein an interval of an equivalent optical path length of
at least 5 mm is provided between a surface of the dust-proofing
member and the photoelectrically converting surface of the image
pick-up device; a vibration generating member, for vibrating the
dust-proofing member, arranged outside an area through which the
beams pass through the dust-proofing member, wherein the vibration
generating member includes a piezoelectric element made of
piezoelectric ceramics; and a sealing structure portion arranged at
a portion formed by opposing the image pick-up device and the
dust-proofing member, the sealing structure portion sealing a space
portion that is substantially sealed at peripheral portions of the
image pick-up device and the dust-proofing member.
21. The image pick-up device unit according to claim 20, wherein
the vibration generating member causes the dust-proofing member to
vibrate in a standing wave.
22. The image pick-up device unit according to claim 20, wherein
the dust-proofing member comprises an optical low-pass filter.
23. The image pick-up device unit according to claim 20, wherein
the dust-proofing member comprises an infrared cut-off filter.
24. The image pick-up device unit according to claim 20, wherein
the dust-proofing member comprises a protecting glass of the image
pick-up device.
25. The image pick-up device unit according to claim 20, wherein an
optical low-pass filter is arranged between the image pick-up
device and the dust-proofing member.
26. The image pick-up device unit according to claim 20, wherein an
infrared cut-off filter is arranged between the image pick-up
device and the dust-proofing member.
Description
This application claims the benefit of Japanese Application No.
2002-153018 filed on May 27, 2002, the entire contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image pick-up device unit
having an image pick-up device for obtaining an image signal
corresponding to light irradiated on a photoelectrically converting
surface or a camera having the image pick-up device unit. More
particularly, the present invention relates to the improvement of a
camera, such as an interchangeable single-lens reflex digital
camera.
2. Related Background Art
Recently, digital cameras such as a so-called digital still camera
or a digital video camera (hereinafter, referred to as a digital
camera or simply referred to as a camera) are generally put into
practical use and are widely spread. In the digital cameras, a
subject image formed subject beams), which are transmitted through
a photographing optical system (also referred to as a photographing
lens) is formed onto a photoelectrically converting surface of a
solid image pick-up device arranged at a predetermined position,
such as a CCD (Charge Coupled Device, hereinafter, simply referred
to as an image pick-up device). Further, an electrical image signal
or the like representing a desired subject image is generated by
using an photoelectrically converting action of the image pick-up
devices. A signal based on the image signal and the like are
outputted to a predetermined display device such as an LCD (Liquid
Crystal Display) and an image or the like is displayed. The image
signal or the like generated by the image pick-up device is
recorded to a predetermined recording area of a predetermined
recording medium as predetermined-format image data. Further, the
image data recorded to the recording medium is read and the image
data is converted to become an image signal which is optimum for a
display using the display device. Thereafter, an image
corresponding thereto is displayed based on the processed image
signal.
In general, digital cameras have an optical finder device for
observing, prior to a photographing operation, a desired subject as
a photographing target and for setting a photographing range
including the subject.
In general, a so-called single-lens reflex finder device is used as
the optical finder device. In this single-lens reflex finder
device, the advancing direction of the subject beams transmitted
through the photographing optical system is bent by using a
reflecting member arranged on the optical axis of the photographing
optical system such that the subject image for observation is
formed at a predetermined position. On the other hand, upon the
photographing operation, the reflecting member is evacuated from
the optical axis of the photographing optical system, thereby
guiding the subject beams onto a light receiving surface of the
image pick-up device, that is, onto a photoelectrically converting
surface thereof and forming the subject image for photographing on
the photographically converting surface.
Furthermore, recently, a so-called interchangeable lens digital
camera having the single-lens reflex finder device is generally put
into practical use. In the interchangeable lens digital camera, the
photographing optical system is detachable to a camera main body,
and a plurality of types of the photographing optical systems are
selectively used in the single-camera main body by arbitrarily
detaching and exchanging a desired photographing optical system in
accordance with user's desire.
In the above-mentioned interchangeable lens digital camera, dust
and the like floating in the air possibly enter the camera main
body upon detaching the photographing optical system from the
camera main body. Various mechanisms which are mechanically
operated such as a shutter and a stop mechanism are arranged in the
camera main body and thus, dust is possibly generated from the
various mechanisms during the operation.
Upon detaching the photographing optical system from the camera
main body, the light receiving surface (also referred to as the
photoelectrically converting surface) of the image pick-up device
arranged in the rear of the photographing optical system is exposed
in the ambient air of the camera. Therefore, dust and the like are
adhered to the photographing converting surface of the image
pick-up device due to electric charge action and the like.
Further, the conventional digital camera having the interchangeable
lens generally include various optical members, such as a
protecting glass for protecting a light receiving surface of the
image pick-up device, an optical low-pass filter, and an infrared
cut-off filter, in a space between the photoelectrically converting
surface and the photographing optical system. Therefore, the
above-mentioned dust, etc. is adhered to the surfaces of the
various optical members.
In the conventional digital cameras, when the dust, etc. is adhered
to the photoelectrically converting surface of the image pick-up
device or the surfaces of the various optical members, a part of
subject beams which are transmitted through the photographing
optical system and which reach the photoelectrically converting
surface of the image pick-up device is shielded by the dust, etc.
Thus, a predetermined shadow is formed onto the photoelectrically
converting surface. Then, the shadow due to the dust, etc. is
photographed on the image based on the image signal obtained by the
image pick-up device. This causes the deterioration in image
quality.
Then, various means as a dust-proofing structure is proposed for
the conventional digital cameras. For example, the dust-proofing
structure prevents the entering of the dust, etc. in a space
between the optical member and the photographically converting
surface of the image pick-up device by constituting a sealing space
which is sealed from the outside.
However, with the above dust-proofing structure, there is a
possibility that dust, etc. can still be adhered to a surface in
the foremost part of the unit, namely, on the arrangement side of
the photographing optical system as an incident surface of the
subject beams after being transmitted through the photographing
optical system.
In particular, the digital cameras having the interchangeable lens
generally use a focal plane type shutter mechanism arranged near
the image pick-up device. However, the focal plane type shutter
mechanism has many operating members and therefore dust, etc. is
caused by operating the operating members.
Then, for example, Japanese Patent Publication No. 2809133
discloses means by which the image based on the obtained image
signal is prevented from an adverse influence due to the adhesion
of dust to the surface of the optical members provided in front of
the image pick-up device (photoelectrically converting device).
In the image pick-up device unit disclosed in Japanese Patent
Publication No. 2809133, the dimension of an interval between a
beam incident surface and a light receiving surface
(photoelectrically converting surface) of a photoelectrically
converting device is regulated by a predetermined condition formula
on a package (unit) which seals the photoelectrically converting
device (image pick-up device). The dimension of the interval for
satisfying the condition formula sets positions of the beam
incident surface of the package and the light receiving surface of
the photoelectrically converting device.
Consequently, if dust is adhered to the beam incident surface of
the package, the influence from the shade formed by the dust to the
optical image based on an electrical signal obtained by the
photoelectrically converting device is suppressed.
The means disclosed in Japanese Patent Publication No. 2809133 is a
technology which is applied to the package of the photoelectrically
converting device for focal detection. This means is effective to
obtain the optical image for the focal detection without trouble.
However, the means cannot be applied to an image pick-up device
unit of a camera such as a digital camera for obtaining the image
signal indicating an image by the image pick-up device. That is, a
trouble can be caused upon displaying the optical image based on
the obtained image signal (image), even if the image signal is
proper for a focal detecting accuracy.
Further, the means disclosed in Japanese Patent Publication No.
2809133 has the following problems because the size of the dust
particles is not considered.
In other words, in the means disclosed in Japanese Patent
Publication No. 2809133, the size of a shade formed by the dust,
etc. adhered to the beam incident surface of the package is
regulated by a predetermined calculating formula. In this case, the
size of the shade formed by the dust, etc. is set to be 15 times or
more of a pixel interval (pitch) of the photoelectrically
converting device. Thus, the influence on the image formed on the
light receiving surface of the photoelectrically converting device
due to the shade is suppressed.
However, of course, the size of the shade formed by the dust
depends on the size of the dust, etc. As the size of the dust
increases, the shade is expanded more widely on the
photoelectrically converting surface. In this case, the density of
the shadow is not decreased. Therefore, the shade adversely
influences on the image formed onto the light receiving surface of
the photoelectrically converting device. The shade causes the
deterioration in picture quality of the image based on the obtained
image signal.
Namely, if the beam incident surface of the package is regulated in
accordance with the dimension of the distance regulated by the
means disclosed in Japanese Patent Publication No. 2809133, the
shade formed by the dust adversely influences on the image
depending on the size of the dust particles adhered to the beam
incident surface.
On the contrary, in the means disclosed in Japanese Patent
Publication No. 2809133, upon using the beam incident surface
having the dimension of the interval between the beam incident
surface of the package and the light receiving surface of the
photoelectrically converting device, which is regulated by the
above calculation, even when there is a possibility that the shade
adversely influence on the image, no trouble can actually be caused
depending on the size of the dust particles adhered to the beam
incident surface.
The above-mentioned contradiction due to the usage of the means
disclosed in Japanese Patent Publication No. 2809133 is caused
because the size of the dust particles is not considered in the
disclosed means.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a
camera and an image pick-up device unit used for the camera, in
which a shade formed by dust, etc. adhered to a surface of an
optical member provided in front of an image pick-up device does
not exert any adverse influence on an image formed and displayed on
an image signal that is obtained by the image pick-up device.
Briefly, according to a first aspect of the invention, a camera
comprises: an image pick-up device which obtains an image signal
corresponding to beams irradiated onto a photoelectrically
converting surface thereof; a photographing lens which inputs a
subject image onto the photoelectrically converting surface of the
image pick-up device; an image signal processing circuit which
converts an image signal obtained from the image pick-up device,
corresponding to an image formed onto the photoelectrically
converting surface of the image pick-up device, into a signal
suitable to recording; a dust-proofing member having a
substantially circular or polygonal plate-shape and comprising a
transparent portion at an area having at least a predetermined
length in a radial direction from a center of the dust-proofing
member, wherein the transparent portion is opposed to a front of an
optical device at a predetermined interval, and wherein an interval
of an equivalent optical path length of at least 5 mm is provided
between a surface of the dust-proofing member and the
photoelectrically converting surface of the image pick-up device;
and a sealing structure portion arranged at a portion formed by
opposing the image pick-up device and the dust-proofing member, the
sealing structure portion sealing a space portion that is
substantially sealed at peripheral portions of the image pick-up
device and the dust-proofing member.
According to a second aspect of the invention, a camera comprises:
an image pick-up device which obtains an image signal corresponding
to beams irradiated onto a photoelectrically converting surface
thereof; an optical member having a first surface opposed to a
front of the image pick-up device at a predetermined interval; and
a sealing structure portion arranged at a portion formed by
opposing the image pick-up device and a dust-proofing member, the
sealing structure portion sealing a space portion that is
substantially sealed at peripheral portions of the image pick-up
device and the dust-proofing member, wherein a dimension of an
interval between the photoelectrically converting surface of the
image pick-up device and a second surface of the optical member is
set such that when positioning an object having a diameter of 1/10
or less of an exit pupil of a photographing lens on the second
surface of the optical member, a density of a shade formed onto the
photoelectrically converting surface is approximately 5% or less of
a density of a shade formed by the object when placing the second
surface of the optical member at a position of an equivalent
optical path length of 1 mm in air from the photoelectrically
converting surface.
According to a third aspect of the invention, an image pick-device
unit comprises: an image pick-up device which obtains an image
signal corresponding to beams irradiated onto a photoelectrically
converting surface thereof; an optical member having a first
surface opposed to a front of the image pick-up device at a
predetermined interval; and a sealing structure portion arranged at
a portion formed by opposing the image pick-up device and a
dust-proofing member, and sealing a space portion that is
substantially sealed at peripheral portions of the image pick-up
device and the dust-proofing member, wherein a condition for
preventing formation of an original shade of an object onto a
second surface of the optical member is set to establish a
relationship of an equivalent optical path length L in air between
the object and the photoelectrically converting surface of the
image pick-up device, such that: L>A.times.d/D where a diameter
of an exit pupil of a photographing lens is designated by .phi.D, a
diameter of the object is by .phi.d, and an equivalent optical path
length in air from a position of the exit pupil to the
photographing converting surface of the image pick-up device is
designated by A.
According to a forth aspect of the invention, an image pick-up
device unit comprises: an image pick-up device which obtains an
image signal corresponding to beams irradiated onto a
photoelectrically converting surface thereof; an optical member
having a first surface opposed to a front of the image pick-up
device at a predetermined interval; and a sealing structure portion
arranged at a portion formed by opposing the image pick-up device
and a dust-proofing member, the sealing structure portion sealing a
space portion that is substantially sealed at peripheral portions
of the image pick-up device and the dust-proofing member, wherein
an interval between the photoelectrically converting surface of the
image pick-up device and a second surface of the optical member is
set to have a dimension of an interval for preventing the formation
of an original shade of an object on the second surface of the
optical member onto the photoelectrically converting surface of the
image pick-up device.
According to a fifth aspect of the invention, a camera comprises: a
photographing lens; an image pick-up device which obtains an image
signal corresponding to beams irradiated onto a photoelectrically
converting surface thereof; an optical member having a first
surface opposed to a front of the image pick-up device at a
predetermined interval; and a sealing structure portion arranged at
a portion formed by opposing the image pick-up device and a
dust-proofing member, the sealing structure portion sealing a space
portion that is substantially sealed at peripheral portions of the
image pick-up device and the dust-proofing member, wherein an
interval between the photoelectrically converting surface of the
image pick-up device and a second surface of the optical member is
set to have a dimension of an interval for preventing formation of
an original shade of an object onto the second surface of the
optical member onto the photoelectrically converting surface of the
image pick-up device.
The above-mentioned and other objects and benefits of the present
invention will be obvious from the following detailed
description.
According to the present invention, there are provided the camera
and the image pick-up device unit used for the camera, in which the
shade formed by dust, etc. adhered to the surface of the optical
member provided in front of the image pick-up device does not exert
any adverse influence on the image formed and displayed based on
the image signal that is obtained by the image pick-up device.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view schematically showing the internal
structure of a camera by cutting off a part of the camera according
to a first embodiment of the present invention;
FIG. 2 is a block diagram schematically showing mainly the
electrical structure of the camera shown in FIG. 1;
FIG. 3 is a diagram showing by extracting a part of an image
pick-up device unit in the camera shown in FIG. 1, that is, a
main-part exploded perspective view showing the disassembled image
pick-up device unit;
FIG. 4 is a perspective view showing a cut-off part of the
assembled image pick-up device unit in the camera shown in FIG.
1;
FIG. 5 is a sectional view along a cut-off plane of FIG. 4;
FIG. 6 is a front view showing by extracting only a dust-proofing
filter and a piezoelectric element integrated with the
dust-proofing filter in the image pick-up device unit in the camera
shown in FIG. 1;
FIG. 7 is a sectional view along a line 7--7 shown in FIG. 6,
namely showing one example of the change in status of the
dust-proofing filter and the piezoelectric element upon applying a
voltage to the piezoelectric element shown in FIG. 6;
FIG. 8 is a sectional view along a line 8--8 shown in FIG. 6,
namely showing another example of the change in status of the
dust-proofing filter and the piezoelectric element upon applying
the voltage to the piezoelectric element shown in FIG. 6;
FIG. 9 is a front view showing by extracting only the dust-proofing
filter and the piezoelectric element integrated with the
dust-proofing filter in the image pick-up device unit in the camera
shown in FIG. 1;
FIG. 10 is a sectional view along a line 10--10 shown in FIG. 9,
namely showing another example of the change in status in the
dust-proofing filter and the piezoelectric element upon applying
the voltage to the piezoelectric element shown in FIG. 9;
FIG. 11 is a sectional view along a line 11--11 shown in FIG. 9,
namely showing another example of the change in status of the
dust-proofing filter and the piezoelectric element upon applying
the voltage to the piezoelectric element shown in FIG. 9;
FIG. 12 is a conceptual diagram of the present invention;
FIG. 13 is diagram showing a relationship between the distance from
a photoelectrically converting surface of the image pick-up device
in the camera to the position of an object such as dust and the
density of a shade of the object formed onto the photoelectrically
converting surface of in the present invention;
FIG. 14 is a perspective view showing by extracting a part forming
an image pick-up device unit in a camera according to a second
embodiment of the present invention, that is, showing a cut-off
part of the assembled image pick-up device unit;
FIG. 15 is a sectional view along a cut-off plane in FIG. 14;
FIG. 16 is a perspective view showing by extracting a part forming
an image pick-up device unit in a camera according to a third
embodiment of the present invention, that is, showing a cut-off
part of the assembled image pick-up device unit; and
FIG. 17 is a sectional view along a cut-off plane in FIG. 16.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
First, a description is given of the schematic structure of a
camera according to a first embodiment of the present
invention.
FIGS. 1 and 2 are diagrams showing the schematic structure of the
camera according to the first embodiment of the present invention.
FIG. 1 is a perspective view schematically showing the internal
structure of a cut-off part of the camera, and FIG. 2 is a block
diagram schematically showing the main electrical structure of the
camera.
According to the first embodiment, a camera 1 comprises a camera
main body unit 11 and a lens barrel 12 which are provided
separately. The camera main body unit 11 and the lens barrel 12 are
detachable from each other.
The lens barrel 12 holds a photographing optical system
(photographing lenses) 12a comprising a plurality of lenses and a
driving mechanism of the lenses. The photographing optical system
12a comprises a plurality of optical lenses for forming a subject
image formed by subject beams by transmitting the beams from a
subject at a predetermined position (at a predetermined position on
a photoelectrically converting surface 27h of an image pick-up
device 27, which will be described later. Refer to FIG. 5). The
lens barrel 12 is projected toward the front side of the camera
main body unit 11.
The lens barrel 12 is a generally-used type used in conventional
cameras. Therefore, a description of the detailed structure is
omitted.
The camera main body unit 11 is a so-called single-lens reflex
camera comprising various members therein, and further having a
photographing optical system attaching unit (referred to as a
photographing lens attaching unit) 11a in front thereof as a
connecting member for detachably arranging the lens barrel 12 for
holding the photographing optical system 12a.
In other words, an opening for exposure having a predetermined
diameter for guiding the subject beams in the camera main body unit
11 is formed substantially in the center in front of the camera
main body unit 11. The photographing optical system attaching unit
11a is formed at a peripheral portion of the opening for
exposure.
The above-mentioned photographing optical system attaching unit 11a
is arranged in front of an outer-surface side of the camera main
body unit 11. In addition, various operating members for operating
the camera main body unit 11, e.g., a release button 17 for
generating an instruction signal to start the photographing
operation and the like are arranged at a predetermined position on
an upper-surface portion or a back-surface portion of the camera
main body unit 11. Since the operating members do not directly
relate to the present invention, a description and an illustration
of the operating members except for the release button 17 are
omitted for the purpose of preventing the complication of the
drawing.
Referring to FIG. 1, in the camera main body unit 11, various
members are arranged at predetermined positions. For example, the
camera main body unit 11 comprises: a finder device 13 forming a
so-called observation optical system, provided for forming a
desired subject image formed by the photographing optical system
12a at a predetermined position different from that on the
photoelectrically converting surface 27h (refer to FIG. 5) of the
image pick-up device 27 (refer to FIG. 2); a shutter unit 14 having
a shutter mechanism and the like for controlling an irradiation
time and the like of the subject beams onto the photoelectrically
converting surface 27h of the image pick-up device 27; an image
pick-up device unit 15 as an assembly, including the shutter unit
14, the image pick-up device 27 for obtaining an image signal
corresponding to the subject image formed based on the subject
beams which are transmitted through the photographing optical
system 12a, and a dust-proofing filter 21 (which will be described
in detail later) having optical members, etc., as a dust-proofing
member for preventing the adhesion of the dusts and the like to the
photoelectrically converting surface 27h of the image pick-up
device 27, arranged at a predetermined position in front of the
photoelectrically converting surface 27h; and a plurality of
circuit boards (only a main circuit board 16 is illustrated in FIG.
1) such as a main circuit board 16 on which various electrical
members constituting an electrical circuit, e.g., an image signal
processing circuit 16a (refer to FIG. 2) for various signal
processing to the image signal obtained by the image pick-up device
27, are mounted.
The finder device 13 comprises a reflecting mirror 13b for bending
and guiding an optical axis of the subject beams transmitted
through the photographing optical system 12a to an observation
optical system, a roof prism 13a for receiving the beams outputted
from the reflecting mirror 13b and for forming an erecting image,
an ocular lens 13c for enlarging the image formed by the roof prism
13a and for forming an image optimum for observation, and the
like.
The reflecting mirror 13b is movable between a position evacuating
from the optical axis of the photographing optical system 12a and a
predetermined position on the optical axis, and is arranged at a
predetermined angle, e.g., 45.degree. with respect to the optical
axis of the photographing optical system 12a in a normal status.
Thus, the optical axis of the subject beams transmitted through the
photographing optical system 12a is bent by the reflecting mirror
13b when the camera 1 is in the normal status, and is reflected to
the roof prism 13a arranged in an upper direction of the reflecting
mirror 13b.
Upon executing the photographing operation of the camera 1, the
reflecting mirror 13b is moved to a predetermined position
evacuated from the optical axis of the photographing optical system
12a during the actual exposure operation. Consequently, the subject
beams are guided to the image pick-up device 27 side and irradiate
the photoelectrically converting surface 27h.
The shutter unit 14 applies a focal plane type shutter mechanism,
driving circuit for controlling the operation of the shutter
mechanism, etc. which are generally used in the conventional
cameras. Therefore, a description of the detailed structure is
omitted.
As mentioned above, a plurality of circuit boards are arranged in
the camera 1, and form various electrical circuits. Referring to
FIG. 2, as the electrical structure, the camera 1 comprises: a CPU
41 as a control circuit for systematically controlling the entire
camera 1; the image signal processing circuit 16a for performing
various signal processing such as signal processing for converting
the image signal obtained by the image pick-up device 27 into a
signal suitable to a recording format; a work memory 16b for
temporarily recording the image signal and image data processed by
the image signal processing circuit 16a and various information in
associated therewith; a recording medium 43 for recording the image
data for recording in a predetermined format generated by the image
signal processing circuit 16a to a predetermined area; a recording
medium interface 42 for electrically connecting the recording
medium 43 to the electrical circuits of the camera 1; a display
unit 46 comprising a liquid crystal display device (LCD) for
displaying the image; a display circuit 47 for electrically
connecting the display unit 46 to the camera 1, receiving the image
signal processed by the image signal processing circuit 16a, and
generating an image signal for display optimum to the display
operation by using the display unit 46; a battery 45 comprising a
secondary battery such as a dry cell; a power supply circuit 44 for
receiving power from the battery 45 or from external power supply
(AC) supplied by a predetermined connection cable (not shown),
controlling the power to match the operation of the camera 1, and
supplying electricity to the electrical circuits; and a
dust-proofing member driving unit 48 as the electrical circuit for
driving the dust-proofing filter 21 included in the image pick-up
device unit 15, comprising an oscillator, and the like.
Next, a detailed description is given of the image pick-up device
unit 15 in the camera 1 according to the first embodiment.
FIGS. 3 to 5 are diagrams showing by extracting a part of the image
pick-up device unit in the camera 1 according to the first
embodiment. FIG. 3 is a main-part exploded perspective view showing
the schematic structure of the disassembled image pick-up device
unit. FIG. 4 is a perspective view showing a cut-off part of the
assembled image pick-up device unit. FIG. 5 is a sectional view
along a cut-off plane shown in FIG. 4.
According to the first embodiment, as mentioned above, the image
pick-up device unit 15 in the camera 1 is a unit comprising a
plurality of members such as the shutter unit 14. However,
referring to FIGS. 3 to 5, the main portion is only shown and an
illustration of the shutter unit 14 is omitted. For the purpose of
showing a positional relationship of the members, referring to
FIGS. 3 to 5, the image pick-up device 27 is loaded while the
members are provided near the image pick-up device unit 15, and the
main circuit board 16 on which the image pick-up system electrical
circuits comprising the image signal processing circuit 16a and the
work memory 16b are mounted is illustrated. The main circuit board
16 is one of main circuit boards generally used in the conventional
cameras, and a detailed description thereof is omitted.
The image pick-up device unit 15 comprises: the image pick-up
device 27 comprising the CCD and the like, which obtains the image
signal corresponding to the light transmitted through the
photographing optical system 12a and irradiated to the
photoelectrically converting surface 27h thereof; the image pick-up
device fixing plate 28 comprising a thin-sheet member for fixing
and supporting the image pick-up device 27; an optical low-pass
filter (hereinafter, referred to as an optical LPF) 25 arranged on
the side of the photoelectrically converting surface 27h of the
image pick-up device 27, as an optical device which is formed to
remove high frequency components from the subject beams transmitted
and irradiated through the photographing optical system 12a; a
low-pass filter supporting member 26 provided in the periphery
between the optical LPF 25 and the image pick-up device 27, which
is made of substantially-frame-shaped elastic members; an image
pick-up device accommodating case member 24 (hereinafter, referred
to as a CCD case 24) which accommodates, fixes, and holds the image
pick-up device 27, supports the optical LPF 25 (optical device) in
contact with a peripheral portion or an adjacent portion of the
optical LPF 25 and which comes into closely contact with a
dust-proofing filter supporting member 23, which will be described
later, at a predetermined portion; the dust-proofing filter
supporting member 23 which is arranged in front of the CCD case 24
and comes into contact with a dust-proofing filter 21
(dust-proofing member) at a peripheral portion or an adjacent
portion thereof and supports it; the dust-proofing filter 21 as a
dust-proofing member, which is supported by the dust-proofing
filter supporting member 23 and which is arranged at a
predetermined position, at a predetermined interval to the optical
LPF 25, in the front of the optical LPF 25 on the side of the
photoelectrically converting surface 27h of the image pick-up
device 27; a piezoelectric element 22 annularly arranged at a
peripheral portion of the dust-proofing filter 21 for applying
predetermined vibrations to the dust-proofing filter 21, and which
comprises an electromechanical transducing device such as a
piezoelectric ceramic; a pressing member 20 comprising an elastic
member which airtightly joints the dust-proofing filter 21 to the
dust-proofing filter supporting member 23; and the like.
The image pick-up device 27 obtains the image signal corresponding
to the subject image formed onto the photoelectrically converting
surface 27h thereof by receiving the subject beams transmitted
through the photographing optical system 12a onto the
photoelectrically converting surface thereof and by performing
photoelectrically converting processing, and applies a CCD (Charge
Coupled Device) for it, for example.
The image pick-up device 27 is mounted at a predetermined position
on the main circuit board 16 with the image pick-up device fixing
plate 28 interposed therebetween. As mentioned above, the image
signal processing circuit 16a, the work memory 16b, etc. are
mounted on the main circuit board 16 such that an output signal
from the image pick-up device 27, that is, the image signal
obtained by the photoelectrically converting processing is
electrically transmitted to the image signal processing circuit 16a
or the like.
The signal processing in the image signal processing circuit 16a
includes various signal processing, for example, processing in
which the image signal obtained from the image pick-up device 27,
as the one corresponding to the image formed onto the
photoelectrically converting surface 27h of the image pick-up
device 27 by the photographing optical system 12a held in the lens
barrel 12 loaded to the photographing optical system attaching unit
11a, is converted into a signal matching the recording. The
above-mentioned signal processing is the same as processing for
treating a digital image signal, which is commonly performed in the
general digital cameras. Therefore, a detailed description of
various signal processing which is usually executed in the camera 1
is omitted.
The optical LPF 25 is arranged in front of the image pick-up device
27 with being sandwiched by the low-pass filter supporting member
26 therebetween. The CCD case 24 is arranged to cover the optical
LPF 25.
That is, an opening 24c which is rectangular-shaped and
substantially in the center is provided for the CCD case 24. The
optical LPF 25 and the image pick-up device 27 are arranged from
the back side of the opening 24c. Referring to FIGS. 4 and 5, a
step portion 24a whose cross section is substantially L-shaped is
formed at an inner peripheral portion of the back side of the
opening 24c.
As mentioned above, the low-pass filter supporting member 26 made
of the elastic member or the like is arranged between the optical
LPF 25 and the image pick-up device 27. In the peripheral portion
in front of the image pick-up device 27, the low-pass filter
supporting member 26 is arranged at a position for evacuating a
valid range of the beams incident on the photoelectrically
converting surface 27h at the periphery of the image pick-up device
27 in the front thereof, and is abutted onto an adjacent portion of
the periphery behind the optical LPF 25. The airtightness is
substantially held between the optical LPF 25 and the image pick-up
device 27. Thus, elastic force generated by the low-pass filter
supporting member 26 acts to the optical LPF 25 in the optical axis
direction.
Then, the peripheral portion in front of the optical LPF 25
airtightly comes into contact with the step portion 24a of the CCD
case 24. Thus, the position of the optical LPF 25 in the optical
axis direction is regulated against the elastic force which is
generated by the low-pass filter supporting member 26 and tends to
displace the optical LPF 25 in the optical axis direction.
In other words, the optical LPF 25 inserted from the back side into
the opening 24c of the CCD case 24 is subjected to the position
regulation in the optical direction by the step portion 24a.
Consequently, it is possible to prevent the optical LPF 25 from
breaking away from the inside of the CCD case 24 to the front
side.
As mentioned above, after inserting the optical LPF 25 in the
opening 24c of the CCD case 24 from the back side, the image
pick-up device 27 is arranged on the back side of the optical LPF
25. In this case, the low-pass filter supporting member 26 is
sandwiched between the optical LPF 25 and the image pick-up device
27 in the peripheral portion.
Further, as mentioned above, the image pick-up device 27 is mounted
on the main circuit board 16 via the image pick-up device fixing
plate 28 interposed. The image pick-up device fixing plate 28 is
fixed to a screw hole 24e from the back of the CCD case 24 by a
screw 28b via a spacer 28a interposed. The main circuit board 16 is
also fixed to the image pick-up device fixing plate 28 by a screw
16d via a spacer 16c interposed.
In front of the CCD case 24, the dust-proofing filter supporting
member 23 is fixed to the screw hole 24b of the CCD case 24 by a
screw 23b. In this case, a circumferential groove 24d is
substantially annularly formed at a predetermined position in front
of the CCD case 24 in the peripheral side thereof, as will be
described in detail in FIGS. 4 and 5. On the other hand, at a
predetermined position on the back and the peripheral side of the
dust-proofing filter supporting member 23, an annular convex
portion 23d (not shown in FIG. 3) corresponding to the
circumferential groove 24d of the CCD 24 is formed throughout the
circumference with a substantially annular shape. Therefore, by
fitting the annular convex portion 23d to the circumferential
groove 24d, the CCD case 24 and the dust-proofing filter supporting
member 23 are substantially airtightly fit mutually to in an
annular area, that is, in an area in which the circumferential
groove 24d and the annular convex portion 23d are formed.
The dust-proofing filter 21 is an optical member which is
circularly or polygonally plate-shaped as a whole, wherein at least
an area having a predetermined length in a radial direction from
the center of the dust-proofing filter 21 is formed into a
transparent portion. The transparent portion is an optical member
which is arranged and opposed at the front of the optical LPF 25 at
a predetermined interval.
At the peripheral portion of one surface of the dust-proofing
filter 21 (at the back surface side thereof according to the first
embodiment), the piezoelectric element 22 as the predetermined
member for vibration comprising an electromechanical transducing
device for vibrating the dust-proofing filter 21 is integrally
formed, by using adhering means such as an adhesive. The
piezoelectric element 22 applies predetermined vibrations to the
dust-proofing filter 21 by applying a predetermined driving voltage
from the outside.
The dust-proofing filter 21 is fixed and held by the pressing
member 20 made of the elastic member such as a plate-shaped spring
so as to airtightly joint to the dust-proofing filter supporting
member 23.
A circular or polygonal opening 23f is provided substantially in
the center of the dust-proofing filter supporting member 23. The
opening 23f is set to a size large enough to have the subject beams
which are transmitted through the photographing optical system 12a
pass through, and to irradiate the photoelectrically converting
surface 27h of the image pick-up device 27 arranged at the
back.
A wall portion 23e (refer to FIGS. 4 and 5) projecting toward the
front side is annularly formed at a peripheral portion of the
opening 23f. Further, a supporting portion 23c is formed such that
it projects further toward the front side at the edge of the wall
portion 23e.
A plurality of (three, according to the first embodiment)
projecting portions 23a with a substantially rectangular shape are
formed to project toward the front side, near an outer peripheral
portion in front of the dust-proofing filter supporting member 23.
The projecting portions 23a are portions formed to fix the pressing
member 20 for fixing and holding the dust-proofing filter 21. The
pressing member 20 is fixed by fastening means such as fixing
screws 20a to the edges of the projecting portions 23a.
The pressing member 20 is a member made of the elastic member such
as a plate spring, and a basic end portion of the pressing member
20 is fixed to the projecting portion 23a. Further, a free end
portion thereof is abutted on an outer peripheral portion of the
dust-proofing filter 21, thereby pressing the dust-proofing filter
21 toward the side of the dust-proofing filter supporting member
23, that is, in the optical axis direction.
In this case, a predetermined portion of the piezoelectric element
22 arranged at the outer peripheral portion at the back of the
dust-proofing filter 21 is abutted onto the supporting portion 23c,
thereby regulating the positions of the dust-proofing filter 21 and
the piezoelectric element 22 in the optical axis direction.
Therefore, the dust-proofing filter 21 is fixed and held to be
airtightly jointed to the dust-proofing filter supporting member 23
with the piezoelectric element 22 interposed therebetween.
In other words, the dust-proofing filter supporting member 23 is
airtightly jointed to the dust-proofing filter 21 via the
piezoelectric element 22 interposed by a pressing force generated
by the pressing member 20.
As mentioned above, with respect to the dust-proofing filter
supporting member 23 and the CCD case 24, the circumferential
groove 24d and the annular convex portion 23d (refer to FIGS. 4 and
5) are substantially airtightly fixed. Further, the dust-proofing
filter supporting member 23 is airtightly jointed to the
dust-proofing filter 21 via the piezoelectric element 22 interposed
by the pressing force generated by the pressing member 20. The
optical LPF 25 arranged to the CCD case 24 is substantially
airtightly arranged between the peripheral portion in front of the
optical LPF 25 and the step portion 24a of the CCD case 24.
Further, the image pick-up device 27 is arranged at the back of the
optical LPF 25 via the low-pass filter supporting member 26
interposed. The airtightness is substantially held also between the
optical LPF 25 and the image pick-up device 27.
Therefore, in a space formed by opposing the optical LPF 25 and the
dust-proofing filter 21, a predetermined void portion 51a is
formed. A space portion 51b is formed on the peripheral side of the
optical LPF 25, that is, by the CCD case 24, the dust-proofing
filter supporting member 23, and the dust-proofing filter 21. The
space portion 51b is a sealed space formed projecting toward the
outside of the optical LPF 25 (refer to FIGS. 4 and 5). Further,
the space portion 51b is set to be wider than the void portion 51a.
A space containing the void portion 51a and the space portion 51b
becomes a sealing space 51 which is substantially airtightly sealed
by the CCD case 24, the dust-proofing filter supporting member 23,
the dust-proofing filter 21, and the optical LPF 25 as mentioned
above.
As mentioned above, according to the first embodiment, the image
pick-up device unit 15 in the camera has the sealing structure
portion forming the sealing space 51 which is substantially sealed
and which is formed at the peripheral portions of the optical LPF
25 and the dust-proofing filter 21, including the void portion 51a.
The sealing structure portion is arranged to the outside the
peripheral portion or the adjacent portion of the optical LPF
25.
Namely, according to the first embodiment, the sealing structure
portion further comprises the dust-proofing filter supporting
member 23 for supporting the dust-proofing filter 21 in contact
with the peripheral portion or the adjacent portion thereof, the
CCD case 24 which supports the optical LPF 25 in contact with the
peripheral portion or the adjacent portion thereof and which is
arranged airtightly in contact with the dust-proofing filter
supporting member 23 at the predetermined portion of the CCD case
24, and the like. That is, the dust-proofing filter 21 functions as
a protecting glass which protects the front side of the image
pick-up device 27 and which forms a part of the sealing structure
portion.
According to the first embodiment, the camera with the
above-mentioned structure is constructed such that the
dust-proofing filter 21 is opposed to a predetermined position in
front of the image pick-up device 27, and the sealing space 51 is
sealed at the peripheries of the photoelectrically converting
surface 27h of the image pick-up device 27 and the dust-proofing
filter 21. Consequently, the adhesion of dust, etc. to the
photoelectrically converting surface 27h of the image pick-up
device 27 is prevented.
In this case, by applying a periodic voltage to the piezoelectric
element 22 arranged integrally with the peripheral portion of the
dust-proofing filter 21 and by applying predetermined vibrations to
the dust-proofing filter 21, dust and the like to be adhered to an
exposure surface (refer to reference numeral 21h shown in FIG. 5)
in front of the dust-proofing filter 21 are removed.
FIG. 6 is a front view showing by extracting only the dust-proofing
filter 21 and the piezoelectric element 22 arranged integrally
therewith in the image pick-up device unit 15 in the camera 1.
FIGS. 7 and 8 shows the change in status of the dust-proofing
filter 21 and the piezoelectric element 22 upon applying a driving
voltage to the piezoelectric element 22 shown in FIG. 6. FIG. 7 is
a sectional view along a line 7--7 shown in FIG. 6, and FIG. 8 is a
sectional view along a line 8--8 shown in FIG. 6.
When a negative (-) voltage is applied to the piezoelectric element
22, the dust-proofing filter 21 is modified as shown by a solid
line in FIGS. 7 and 8. On the other hand, when a positive (+)
voltage is applied to the piezoelectric element 22, the
dust-proofing filter 21 is modified as shown by a dotted line in
FIGS. 7 and 8.
In this case, an amplitude is substantially equal to zero at a node
upon vibrations as shown by reference symbol 21a shown in FIGS. 6
to 8. Thus, the supporting portion 23c of the dust-proofing filter
supporting member 23 is abutted onto a portion corresponding to the
node 21a. Consequently, the dust-proofing filter 21 is efficiently
supported without reducing the vibrations.
In this status, the dust-proofing filter driving unit 48 is
controlled at a predetermined timing and the periodic voltage is
applied to the piezoelectric element 22, thereby vibrating the
dust-proofing filter 21. Thus, it is possible to remove dust and
the like adhered to the surface of the dust-proofing filter 21.
A resonant frequency in this case is determined depending on the
plate thickness, the material, and the shape of the dust-proofing
filter 21. In one example shown in FIGS. 6 to 8, a first-degree
vibration is generated, however, the present invention is not
limited to this, and a high-degree vibration may be generated.
In another example shown in FIGS. 9 to 11, a second-degree
vibration is generated to the dust-proofing filter with the same
structure as the example shown in FIGS. 6 to 8.
In this case, FIG. 9 is a front view showing by extracting only the
dust-proofing filter 21 and the piezoelectric element 22 arranged
integrally therewith among members in the image pick-up device unit
15 in the camera 1, similarly to FIG. 6. FIGS. 10 and 11 show the
change in status of the dust-proofing filter 21 and the
piezoelectric element 22 when the voltage is applied to the
piezoelectric element 22 shown in FIG. 9. FIG. 10 is a sectional
view along a line 10--10 shown in FIG. 9. FIG. 11 is a sectional
view along a line 11--11 shown in FIG. 9.
Herein, when a negative (-) voltage is applied to the piezoelectric
element 22, the dust-proofing filter 21 is modified as shown by a
solid line in FIGS. 10 and 11. On the other hand, when a positive
(+) voltage is applied to the piezoelectric element 22, the
dust-proofing filter 21 is modified as shown by a dotted line in
FIGS. 10 and 11.
In this case, as shown by reference symbols 21a and 21b shown in
FIGS. 9 to 11, the vibration has two pairs of nodes. By setting the
supporting portion 23c of the dust-proofing filter supporting
member 23 such that it is abutted onto a portion corresponding to
the node 21a, the dust-proofing filter 21 is efficiently supported
without reducing the vibration similarly to the above-described
example shown in FIGS. 6 to 8.
In this status, the dust-proofing filter driving unit 48 is
controlled at a predetermined timing and the periodic voltage is
applied to the piezoelectric element 22, thereby vibrating the
dust-proofing filter 21. Thus, it is possible to remove dust and
the like adhered to the surface of the dust-proofing filter 21.
When the first-degree vibration is generated as shown in FIGS. 6 to
8, in the sealing space 51, the amplitude of the dust-proofing
filter 21 generates the change in volume shown by reference symbol
C. As shown in FIGS. 9 to 11, when the second-degree vibration is
generated, the change in volume of the sealing space 51 generated
by the amplitude of the dust-proofing filter 21 corresponds to the
amount obtained by subtracting an area shown by a reference symbol
D2.times.2 from an area shown by a reference symbol D1, that is,
[D1-(D2.times.2)].
The smaller the change in volume to the sealing space 51 is, the
smaller the change in inner pressure is in the sealing space 51.
Therefore, it will be understood that the smaller the change in
volume of the sealing space 51 is, the vibration can more
efficiently be obtained. Thus, in view of the efficiency of the
electromechanical transducing, it is preferable that the generated
vibration is set in a high-degree mode.
As mentioned above, in the image pick-up device unit 15 of the
camera 1 according to the first embodiment, the action of the
piezoelectric element 22 for applying predetermined vibrations to
the dust-proofing filter 21 causes dust adhered to the surface in
front of the dust-proofing filter 21, namely, on a surface 21h on
the side opposed to the photographing optical system 12a (refer to
FIG. 5) to be shaken off. Most of the dust adhered to the surface
21h of the dust-proofing filter 21 is shaken off by the vibrations.
However, some of the dust is not necessarily removed in this case.
In particular, minute dust particles having a small mass are hardly
removed because they are not shaken off by inertia force of the
vibrations.
Here, the dust-proofing filter 21 is arranged at a predetermined
position in a space between the photographing optical system 12a
and the image pick-up device 27 on an optical path of the
photographing optical system 12a. Therefore, the beams from the
subject reach the photoelectrically converting surface 27h of the
image pick-up device 27 via the photographing optical system 12a
and the dust-proofing filter 21 and form an optical image on the
photoelectrically converting surface 27h. In this status, an
operation for obtaining the image signal is executed by driving the
image pick-up device 27.
In this status, when dust is adhered to the surface 21h of the
dust-proofing filter 21, the shade formed by the dust is formed on
the photoelectrically converting surface 27h of the image pick-up
device 27. Then, the shade formed by the dusts is photographed on a
display image formed based on the image signal obtained in this
case.
FIG. 12 is a diagram showing the basic concept of the present
invention, that is, a diagram for explaining a status of forming
the shade of an object such as dust on the photoelectrically
converting surface of the image pick-up device when the object
exists between an exit pupil of the photographing optical system
and the photoelectrically converting surface.
An exit pupil 101 of the photographing optical system (12a not
shown in FIG. 12), an object 100 such as the dusts, and the
photoelectrically converting surface 27h of the image pick-up
device (27) are arranged along an optical axis O of the
photographing optical system (12a). In this case, it is assumed
that,
a diameter of the exit pupil 101=D,
a distance from the exit pupil 101 to the photoelectrically
converting surface 27h=A,
a diameter of the object 100=d, and
a distance from the object 100 to the photoelectrically converting
surface 27h=L.
The beams outputted from the exit pupil 101 and reaching the
photoelectrically converting surface can generally be scattered and
irradiated. Beams O1 shown in FIG. 12 among output beams represents
beams contributing to the formation of an original shade of the
object 100 onto the photoelectrically converting surface 27h among
the beams outputted from the exit pupil 101. When the object 100 is
at a position shown in FIG. 12 (at a position of the equivalent
optical distance L in the air from the photoelectrically converting
surface 27h), the original shade is formed substantially at a
single point having an extremely narrow area shown by reference
numeral 106 on the photoelectrically converting surface 27h. This
portion is referred to as an original shade portion 106.
Beams O2 shown in FIG. 12 represents beams contributing to the
formation of a half shade of the object 100 onto the
photoelectrically converting surface 27h among the beams outputted
from the exit pupil 101. When the object 100 is at the same
position as that shown in FIG. 12 (at a position of the distance
L), the half shade is relatively widely formed as shown by
reference numeral 107. This portion is referred to as a half-shade
portion 107. The half-shade portion 107 has a density lighter than
that of the original shade portion 106.
FIG. 13 is a diagram showing a relationship between the dimension
of an interval from the photoelectrically converting surface 27h of
the image pick-up device 27 to the position of the object 100 such
as dust, namely, the distance L, and the density (darkness or
lightness) of the shade of the object 100 formed onto the
photoelectrically converting surface.
Hereinbelow, it is assumed that the density of the shade on the
optical axis is considered as a reference one (=1 (100%)) when the
equivalent optical distance L in the air from the photoelectrically
converting surface 27h of the image pick-up device 27 to the
position of the dust is 1 mm.
Referring to FIG. 13, as the object 100 such as the dust is more
remote from the photoelectrically converting surface 27h, the shade
of the object 100 formed onto the photoelectrically converting
surface 27h generally become lighter.
As shown in FIG. 13, it is understood that when the distance L
between the object 100 and the photoelectrically converting surface
27h is separated by approximately 5 mm, the density of the shade of
the object 100 formed onto the photoelectrically converting surface
27h is approximately 5% of the density of the shade at the
above-mentioned reference position (L=1 mm). Dust having a particle
size of approximately 1/10 (diameter of 0.2 mm) or less of the exit
pupil have the shade density of 5% or less of that at the reference
position. This shade density does not influence the image.
Therefore, it is preferable that the distance L between the object
100 and the photoelectrically converting surface 27h is 5 mm or
more. The diameter of the object 100 in this case is, e.g., 1/10 or
less of the exit pupil of the photographing lens 12a.
As diameter D of the exit pupil is smaller, the size of the shade
becomes larger. That is, as a stop is smaller, the condition is
that the original shade is easily formed. In the photographing
optical system (photographing lens) 12a used for the conventional
general digital cameras having the interchangeable lens, the
diameter upon using the smallest stop, namely, the diameter d of
the exit pupil is D of approximately 2 mm. When the exit pupil D
has less than the diameter d, the resolution and the sharpness are
extremely decreased due to a light diffraction phenomenon.
Therefore, this results in the reduction in image quality and, the
use of the exit pupil D in this case is unpreferable.
On the other hand, the conventional digital cameras generally
applies a so-called zoom lens capable of zooming a focusing
distance of the photographing optical system 12a. A zoom ratio of
the zoom lens is recently getting higher. For example, a high-ratio
zoom lens is generally put into practical use and spread so as to
easily photograph the image at a long-focusing area having the
focusing distance of approximately 200 mm. Thus, in the case of the
high-ratio zoom lens, the distance A between the exit pupil 101 and
the photoelectrically converting surface 27h is set to be long in
some degree.
As the distance A is longer, the beams outputted from the exit
pupil 101 substantially become parallel. Consequently, as the
distance A is longer, the original shade is easily formed.
In consideration of the foregoing, a condition that the original
shade is easily formed is as follows.
For example, in the case of the zoom lens capable of photographing
the image at the long-focusing area having the focusing distance of
up to 200 mm, the distance A between the exit pupil 101 and the
photoelectrically converting surface 27h is approximately 120 mm.
It is assumed that the diameter D of the exit pupil of the
photographing optical system is 2.4 mm and the distance L between
the object 100 and the photoelectrically converting surface 27h is
5 mm. If the diameter d of the object 100 is 100 .mu.m or more
(d.gtoreq.100 .mu.m), the original shade is formed onto the
photoelectrically converting surface 27h. On the other hand, the
diameter d of the object 100 is less than 100 .mu.m (d<100
.mu.m), only the half shade is formed and the original shade is not
formed.
As a result of an experiment of the present applicant, if the
diameter d is less than 50 .mu.m under the above optical condition,
it is confirmed that the shade does not influence the photographing
image.
Then, the density of the formed shade of the object 100 is
estimated and the influence on the photographing image is further
estimated by examining the half shade in this case.
In this case, it is assumed that a pixel pitch p of the image
pick-up device 27 is 10 .mu.m. Then, by using the conventional
means disclosed in Japanese Patent Publication No. 2809133, the
shade of the object 100 influences on the image formed onto the
photoelectrically converting surface 27h. However, it is confirmed
as the result of the experiment that in consideration of the
diameter d (d<50 .mu.m) of the object 100, the original shade is
not formed and the half shade does not influence the image.
Incidentally, the object 100 having the size of the diameter d
(<50 .mu.m) corresponds to dust formed while operating a movable
member such as the shutter.
As mentioned above, when the diameter d of the object 100 such as
dust is less than 50 .mu.m (d<50 .mu.m), the dimension of the
interval between the photoelectrically converting surface 27h of
the image pick-up device 27 and the position of the object 100
adhered to the surface 21h of the dust-proofing filter 21 on the
photographing lens side is set to have the equivalent optical path
length of 5 mm or more in the air. Then, even if the exit pupil of
the photographing optical system has the smallest stop and the
photographing optical system has the long focusing distance, the
original shade of the object 100 such as the dust is not
formed.
The condition for preventing the formation of the original shade is
as follows. That is, a relationship of L>A.times.d/D is
established
where D: diameter of the exit pupil 101 of the photographing
optical system,
d: diameter of the object 100, and
L: equivalent optical path length from the exit pupil 101 to the
photoelectrically converting surface 27h in the air.
Herein, it is assumed that the equivalent optical path length in
the air is designated by t, an index of refraction of the air is
designated by n, an index of refraction of a predetermined medium
is designated by n', and an optical path length of geometric beams
in the medium is designated by t'. In this case, the following
relationship is established. t=(n/n')/t'
The above-mentioned position setting of the dust-proofing filter
prevents the formation of the dark shade of dust particles having a
diameter of 50 .mu.m or less onto the photoelectrically converting
surface and further prevents a negative influence on the image
quality.
Next, a description is given of the advantageous structure for
removing large dust particles (having a diameter of 50 .mu.m or
more) by vibrating the dust-proofing filter.
In general, it is well known that the setting of a short interval
between the optical LPF 25 and the dust-proofing filter 21
(dust-proofing member) increases an inner pressure of the sealing
space 51 upon vibrating the dust-proofing filter 21 by the
piezoelectric element 22 (member for vibration) because the volume
of the void portion 51a is reduced. However, when the inner
pressure of sealing space 51 is high, the vibration of the
dust-proofing filter 21 by the piezoelectric element 22 is
inhibited.
On the other hand, the setting of a long interval between the
optical LPF 25 and the dust-proofing filter 21 (dust-proofing
member) for the sake of assuring the volume of the sealing space 51
increases the dimension of the image pick-up device unit 15 in the
optical axis direction. Thus, this becomes a factor which inhibits
the reduction in size of the camera 1 in the optical axis
direction.
According to the first embodiment, by providing the space portion
51b outside the peripheral portion or the adjacent portion of the
optical LPF 25, the volume of the sealing space 51 is sufficiently
ensured. Then, the increase in size of the image pick-up device
unit 15 in the optical axis direction is suppressed without
inhibiting the vibration of the dust-proofing filter 21 which is
applied by the piezoelectric element 22. Therefore, this easily
contributes to the reduction in size of the camera 1 in the optical
axis direction.
The vibration of the dust-proofing filter 21 caused by applying a
periodic voltage to the piezoelectric element 22 enables shaking
off relatively large dust particles (e.g., having the diameter of
1/10 or less of the exit pupil diameter of the photographing lens
12a to approximately 50 .mu.m) adhered to the surface of the
dust-proofing filter 21.
In the case of dust particles having a relatively small size, which
are not shaken off by vibrating the dust-proofing filter 21,
namely, dust particles having a size smaller than a diameter of 50
.mu.m which can be caused by the operation of the internal
mechanism upon operating the camera 1, the dust-proofing filter 21
and the image pick-up device 27 are arranged in consideration of
the setting of the arrangement position of the dust-proofing filter
21 under the condition that the formation of the original shade of
the dust onto the photoelectrically converting surface 27h is
prevented even when the dust is adhered to the surface 21h of the
dust-proofing filter 21. Thus, the image signal which enables
indicating the preferable image can be obtained from the image
indicated by the obtained image signal without any negative
influence from the dust.
In the camera 1 according to the first embodiment, the
dust-proofing filter supporting member 23 and the CCD case 24 are
separately formed and they are airtightly fit to each other.
However, the present invention is not limited to this and a single
member may be formed by integrating the dust-proofing filter
supporting member 23 and the CCD case 24. An example thereof is
described hereinbelow according to a second embodiment of the
present invention.
According to the second embodiment of the present invention, the
structure is similar to that according to the first embodiment.
Unlike the first embodiment, in place of the dust-proofing filter
supporting member (23) and the CCD case (24), the second embodiment
applies a single member (dust-proofing filter supporting and CCD
case 33) formed by integrating them. Further, unlike the first
embodiment, in place of the optical LPF 25, the second embodiment
applies an optical LPF 25A having the structure slightly different
from that of the optical LPF 25.
Therefore, the same reference numerals as those according to the
first embodiment denote the same components and a detailed
description is omitted. Further, the structure of the entire camera
is not illustrated and is referred to FIGS. 1 and 2.
FIGS. 14 and 15 are diagrams showing by extracting a part of
members forming an image pick-up device unit in a camera according
to the second embodiment of the present invention. FIG. 14 is a
perspective view showing a cut-off part of the assembled image
pick-up device unit, corresponding to FIG. 4 according to the first
embodiment. FIG. 15 is a sectional view along a cut-off plane shown
in FIG. 14, corresponding to FIG. 5 according to the first
embodiment.
Referring to FIGS. 14 and 15, similarly to FIGS. 4 and 5 according
to the first embodiment, only the main portion of the image pick-up
device unit is illustrated and the shutter unit is not shown. For
the purpose of showing the positional relationship of the members,
the main circuit board (16) is shown together.
As mentioned above, in an image pick-up device unit 15A according
to the second embodiment, in place of the dust-proofing filter
supporting member (23) and the CCD case (24) according to the first
embodiment, the single member formed by integrating the
dust-proofing filter supporting member (23) and the CCD case (24),
that is, the dust-proofing filter supporting and CCD case
(hereinafter, briefly referred to as a CCD case) 33 is used.
The CCD case 33 integrally includes a first portion and a second
portion. That is, the first portion functions as the dust-proofing
filter supporting unit for supporting the dust-proofing filter 21
in contact with the peripheral portion or the adjacent portion of
the dust-proofing filter 21. The second portion functions as the
image pick-up device accommodating case unit for accommodating,
fixing, and holding the image pick-up device 27 and for supporting
the optical LPF 25 in contact with the peripheral portion or the
adjacent portion of the optical LPF 25. Thus, the sealing structure
portion is integrally formed.
In the image pick-up device unit 15A of the camera (1) according to
the second embodiment, the sealing structure portion is formed as
follows.
That is, a predetermined void portion 51Aa is formed in a space
formed by opposing the optical LPF 25A and the dust-proofing filter
21. On the peripheral side of the optical LPF 25A, a space portion
51Ab is formed by the CCD case 33 and the dust-proofing filter 21
to be extended towards the outside of the optical LPF 25A. The
space portion 51Ab is set to be wider than the void portion 51Aa. A
space containing the void portion 51Aa and the space portion 51Ab
constitutes a sealing space 51A which is substantially airtightly
sealed by the CCD case 33, the dust-proofing filter 21, and the
optical LPF 25A.
As mentioned above, in the image pick-up device unit 15A in the
camera according to the second embodiment, the sealing structure
portion includes the sealing space 51A which is formed at the
peripheries of the optical LPF 25A and the dust-proofing filter 21
and which is substantially sealed, including the void portion 51Aa.
The sealing structure portion is provided at the position outside
the periphery or the adjacent portion of the optical LPF 25A.
Further, according to the second embodiment, the sealing structure
portion is constituted by the CCD case 33 and the like. The CCD
case 33 is integrally constituted by the first portion for
supporting the dust-proofing filter 21 in contact with the
peripheral portion or the adjacent portion of the dust-proofing
filter 21 and the second portion for supporting the optical LPF 25
in contact with the peripheral portion or the adjacent portion of
the optical LPF 25A.
According to the second embodiment, the optical LPF 25A is formed
by integrating a portion having a function as the optical LPF
(portion shown by reference numeral 25a in FIGS. 14 and 15) and a
portion having a function as the infrared cut-off filter (portion
shown by reference numeral 25b in FIGS. 14 and 15).
Further, according to the second embodiment, the equivalent optical
path length L between the photoelectrically converting surface 27h
of the image pick-up device 27 (refer to FIG. 15) and the surface
21h of the dust-proofing filter 21 in the air is set to be equal to
5 mm or more, similarly to the first embodiment.
Other structures are entirely the same as those according to the
first embodiment.
In the camera (1) with the above structure according to the second
embodiment, the operation upon removing the dusts adhered to the
surface of the dust-proofing filter 21 by vibrating the
dust-proofing filter 21 by using the piezoelectric element 22 is
the same as that according to the first embodiment.
As mentioned above, according to the second embodiment, the same
advantages as those according to the first embodiment are
obtained.
In addition, according to the second embodiment, the optical LPF
25A is formed by integrating the first portion having the function
as the dust-proofing filter supporting unit for supporting the
dust-proofing filter 21 in contact with the peripheral portion or
the adjacent portion thereof and the second portion having the
function as the image pick-up device accommodating case unit for
accommodating, fixing, and holding the image pick-up device 27 and
for supporting the optical LPF 25A in contact with the peripheral
portion or the adjacent portion thereof. Thus, the
photoelectrically converting surface of the image pick-up device
and the dust-proofing filter are accurately positioned. The
simplification of the structure contributes to the reduction in
number of members, the manufacturing process is simplified, and the
manufacturing costs are reduced.
According to the second embodiment, the optical LPF 25A is formed
by integrating the portion (shown by reference numeral 25a in FIGS.
14 and 15) having the function as the optical LPF and the portion
(shown by reference numeral 25b in FIGS. 14 and 15) having the
function as the infrared cut-off filter. However, the present
invention is not limited to this. For example, similarly to the
optical LPF 25 according to the first embodiment, the optical LPF
25A which has the single function as the optical LPF may be
used.
In the camera 1 according to the first and second embodiments, the
optical LPF 25 or 25A is provided. However, the present invention
is not limited to this and may use an image pick-up device unit
having no optical LPF in the camera.
For example, in the case of a digital camera using a numerous-pixel
type image pick-up device in which the number of valid pixels (the
number of pixels used for formation of image data) of the image
pick-up device exceeds the resolution of the lens, the image
pick-up device unit is formed by excluding the optical LPF in front
of the image pick-up device. The present invention can easily be
applied in the above-mentioned case. According to a third
embodiment, an example thereof will be described hereinbelow.
In other words, the structure according to the third embodiment is
substantially the same as that according to the second embodiment.
Unlike the second embodiment, the optical LPF (25A) according to
the second embodiment is excluded and a CCD case 34 for supporting
the dust-proofing filter 21 and for fixing and holding the image
pick-up device 27 is used in place of the CCD case (33) for
supporting the dust-proofing filter 21 and for fixing and holding
the image pick-up device 27 and the optical LPF (25A). Therefore,
the same structure as that according to the second embodiment is
designated by the same reference numeral and is not described in
detail. The structure of the entire camera is not illustrated
similarly to the second embodiment and is referred to in FIGS. 1
and 2 using for the description of the first embodiment.
FIGS. 16 and 17 are diagrams showing by extracting a part of the
image pick-up device unit in the camera according to the third
embodiment of the present invention. FIG. 16 is a perspective view
showing a cut-off part of the assembled image pick-up device unit,
corresponding to FIG. 4 according to the first embodiment or to
FIG. 14 according to the second embodiment. FIG. 17 is a sectional
view along a cut-off plane shown in FIG. 16, corresponding to FIG.
5 according to the first embodiment or to FIG. 15 according to the
second embodiment.
Referring to FIGS. 16 and 17, similarly to FIGS. 4 and 5 according
to the first embodiment and FIGS. 14 and 15 according to the second
embodiment, only the main portion of the image pick-up device unit
is shown and the shutter unit is not shown. The main circuit board
(16) is also similarly illustrated for the purpose of showing the
positional relationship of the members.
As mentioned above, according to the third embodiment, an image
pick-up device unit 15B is formed by excluding the optical LPF 25
or 25A in the camera (1) according to the first or second
embodiment. Further, similarly to the second embodiment, the image
pick-up device unit 15B comprises the dust-proofing filter
supporting and CCD case 34, as an integrated single member in place
of having the dust-proofing filter supporting member (23) and the
CCD case (24) separately according to the first embodiment.
The CCD case 34 integrally includes a first portion and a second
portion. That is, the first portion functions as the dust-proofing
filter supporting unit for supporting the dust-proofing filter 21
in contact with the peripheral portion or the adjacent portion of
the dust-proofing filter 21. The second portion functions as the
image pick-up device accommodating case unit for supporting the
photoelectrically converting surface 27h of the image pick-up
device 27 in contact with the peripheral portion or the adjacent
portion of the image pick-up device 27. Thus, the sealing structure
portion is formed.
The sealing structure portion in the image pick-up device unit 15B
in the camera (1) is structured as follows according to the third
embodiment.
That is, a predetermined void portion 51Ba is formed in a space
formed by opposing the image pick-up device 27 and the
dust-proofing filter 21. A space portion 51Bb is formed by the CCD
case 34 and the dust-proofing filter 21, extending to the outside
of the photoelectrically converting surface 27h on the peripheral
side of the photoelectrically converting surface 27h of the image
pick-up device 27. The space portion 51Bb is set to be wider than
the void portion 51Ba. A space containing the void portion 51Ba and
the space portion 51Bb forms a sealing space 51B which is
substantially airtightly sealed by the CCD case 34, the
dust-proofing filter 21, and the photoelectrically converting
surface 27h of the image pick-up device 27.
As mentioned above, in the image pick-up device unit 15B in the
camera according to the third embodiment, the sealing structure
portion is formed to constitute the sealing space 51B which is
formed at the photoelectrically converting surface 27h of the image
pick-up device 27 and at the periphery of the dust-proofing filter
21, containing the void portion 51Ba, and being substantially
sealed. The sealing structure portion is provided at the position
outside the periphery or adjacent portion of the photoelectrically
converting surface 27h of the image pick-up device 27.
Further, according to the third embodiment, the sealing structure
portion includes the CCD case 34 which is formed by integrating the
first portion and the second portion. That is, the first portion
supports the dust-proofing filter 21 in contact with the peripheral
or the adjacent portion thereof. The second portion supports the
photoelectrically converting surface 27h of the image pick-up
device 27 in contact with the peripheral or the adjacent portion
thereof.
According to the third embodiment, the image pick-up device unit
15B is formed by excluding the optical device as mentioned above.
Therefore, the dust-proofing filter 21 has a transparent portion
which is arranged and opposed to the front of the photoelectrically
converting surface 27h of the image pick-up device 27 at a
predetermined interval.
Further, according to the third embodiment, the equivalent optical
path length L between the photoelectrically converting surface 27h
of the image pick-up device 27 (refer to FIG. 17) and the surface
21h of the dust-proofing filter 21 in the air is set to be equal to
5 mm or more, similarly to the first embodiment.
Other structures are the same as those according to the first and
second embodiments. According to the third embodiment, the
operation upon removing the dusts adhered to the surface of the
dust-proofing filter 21 by vibrating the dust-proofing filter 21 by
using the piezoelectric element 22 is the same as that according to
the first and second embodiments.
As mentioned above, in the camera using the image pick-up device
unit which is formed by excluding the optical LPF 25 according to
the third embodiment, the same advantages as those according to the
second embodiment are obtained.
According to the third embodiment, the optical LPF is formed by
integrating the first portion having the function as the
dust-proofing filter supporting unit for supporting the
dust-proofing filter 21 in contact with the peripheral portion or
the adjacent portion thereof and the second portion having the
function as the image pick-up device accommodating case unit for
supporting the photoelectrically converting surface 27h of the
image pick-up device 27 in contact with the peripheral portion or
the adjacent portion thereof. Thus, the simplification of the
structure contributes to the reduction in number of members, the
manufacturing process is simplified, and the manufacturing costs
are reduced.
According to the third embodiment, similarly to the first and
second embodiments, the dust-proofing filter 21 may use the optical
member having a function of a protecting glass. In addition, the
dust-proofing filter 21 may use the optical member having the
function of the optical low-pass filter or the infrared cut-off
filter.
According to the third embodiment, the camera is formed by
excluding the optical low-path filter (optical LPF; optical device)
according to the first embodiment. Further, the sealing structure
portion is structured by the CCD case (34) which is formed by
integrating the first portion for supporting the dust-proofing
filter 21 and the second portion for supporting the image pick-up
device 27. However, the present invention is not limited to this.
In the example according to the third embodiment, namely, in the
image pick-up device unit having no optical LPF in the camera, the
dust-proofing filter supporting member (23) and the CCD case (24)
may independently be formed similarly to the first embodiment and
they further may airtightly be fit to each other.
It should be understood that the present invention is not limited
to the precise disclosed embodiments, and various changes and
modifications thereof can be made without departing from the spirit
or scope of the invention.
* * * * *